Rockstar Research has found multiple experts that agree it takes 21 days to develop a habit. Breaking a bad habit is a little more difficult but the same time frame can be applied. Many self help programs are based of this hypothesis but it doesn't mean that after 3 weeks, presto magic, everything is better or the habit that you are trying to correct has, in fact, been corrected.
The first three weeks may be the hardest but if you can keep the repetition of the new, desired habit going for three months it will, only then, become the equivalent of something that you don't need to even think about anymore. There will be pitfalls. There will be challenges but there will be a point, around 3 months according to Rockstar Research, that the new behaviour just is.
Three weeks from today is the Nationwide Insurance 10K Run for ASPIRE in Plainview, NY. Three months from today is EagleMan 70.3. While running the NYRR8000 was a step in the right direction this morning (and doing the course clockwise and counterclockwise), put that greasy bacon cheeseburger down, Rockstar, and get into a habit of eating right, training right, because that will lead to experiencing how to celebrate right.